Earth Notes
3:29 am
Mon July 17, 2006

Hot Zone

Flagstaff, AZ – Some of us have to learn hard lessons the hard way. Take the heat. I was warned it gets hot enough in the desert to fry an egg on the sidewalk. I'm not sure about sidewalks, but I did manage to fry one on the hood of a car. During canyon hikes I've seen creeks dry up in the heat of the day, only to run again at night. I've watched ravens pant and lizards sprint across hot sand on their hind legs.

So I knew it gets hot in the desert. But the lesson didn't sink in until I ran out of water and learned how easily a life can balance on only a few sips. Thirst forced me to recalibrate my approach to summer treks. These days I'll start walking before dawn and shade up, if possible, during midday. Above 92 degrees, your body begins gaining more heat than it loses. When the air temperature is 100 degrees you burn twice the energy used to cover the same distance in cooler weather.

At times when I'm walking under the full sun, the story of a cowboy thrown from his horse in the desert comes to mind. He wandered for three days without water until another cowboy found him. Close to death, he was described as sweating blood and fighting buzzards. Blood-sweat, a scientist noted, occurs in the terminal stage of dehydration. It's a hard image to shake.

An exploring party in 1855 encountered extreme conditions above Black Canyon, not far from today's Hoover Dam. On dismounting they found the ground too hot to stand on with moccasins and watched their mules roll on their backs waving their hooves in the air to cool them down. In the same area a few years ago two men died from the combined effects of heat and dehydration. Hikers found one of them incoherent and swinging naked from a tree. They were unable to save him. An hour or two in the desert without water and the mind will turn on itself.

Wild animals have come up with clever ways of handling the heat. Antelope ground squirrels slobber on their chests to take advantage of the evaporative cooler effect, and vultures urinate on their legs. Many desert dwellers burrow underground where the temperature can be half what it is on the surface. Other animals, including some humans I've known, slip into a daily torpor and wait for the cool of evening to revive them.

Yes, it gets hot in the desert. But as a gas station attendant in Gila Bend observed, at least you don't have to shovel it off the sidewalk.

Funding for this commentary was provided by the Arizona Humanities Council